Meat Science 107 (2015) 49–56

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The inclusion of Duroc breed in maternal line affects pork quality and fatty acid profile Verónica Alonso, Erica Muela, Beatriz Gutiérrez, Juan Benito Calanche, Pedro Roncalés, José A. Beltrán ⁎ Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain

a r t i c l e

i n f o

Article history: Received 25 June 2014 Received in revised form 14 April 2015 Accepted 17 April 2015 Available online 24 April 2015 Keywords: Crossbreeding Lipid oxidation Texture Fatty acid composition Meat Pigs

a b s t r a c t The aim of this study was to evaluate the effect of including different percentages of Duroc (D) breed in maternal line [Landrace (LR) × Large White (LW); LR × (LW × D); LR × D] and gender on meat quality and intramuscular (IMF) and subcutaneous (SCF) fatty acid composition. No significant differences were found among dam lines in ultimate pH, L* values and drip and cooking losses. There were higher percentages of saturated fatty acids in LR × D and LR × (LW × D) lines and higher percentages of polyunsaturated fatty acids in LR × LW line in IMF and SCF. Also, LR × D line produced pork with a lower Warner–Bratzler shear force values and higher IMF content and potential of lipid oxidation. Furthermore, the L*, a* and b* values and drip loss were greater in pork from entire males than females. The IMF and SCF of females were more monounsaturated and less polyunsaturated than those from entire males. © 2015 Elsevier Ltd. All rights reserved.

1. Introduction There are many factors that influence final meat quality, e.g. animal nutrition, transport, handling, and stunning, but it is well-known that breed can affect pork quality (Armero et al., 1999; Gil et al., 2008; Pascual et al., 2007; Šimek, Grolichová, Steinhauserová, & Steinhauser, 2004). Thus, breed comparisons are performed quite often when meat quality is a significant consideration (Mörlein, Link, Werner, & Wicke, 2007). The most common crossbreeding used in the intensive pig production in Spain is a three-way cross where the sow is an F1 Landrace × Large White crossbreed and the terminal sire involves well conformed breeds (Oliver et al., 1994), such as Pietrain, Belgian Landrace and Large White. However, the interest in other breeds as a means of increasing heterosis and facilitating development of specialized sired and dam lines has increased (Edwards, Wood, Moncrieff, & Porter, 1992). The Duroc breed, which was introduced in Europe mainly due to its higher intramuscular fat content compared to other breeds (Barton-Gade, 1987), has been used in different pig breeding programmes in Spain. Firstly, Duroc breed is used as a terminal sire when fattening pigs are produced; this breed has an excellent growth rate and resistance to environmental conditions, being free of the halothane gene, and abundant intramuscular fat (Armero et al., 1999; Suzuki, Shibata, Kadowaki, Abe, & Toyoshima, 2003), thereby improving the quality of fresh and dry-cured pork products. Secondly, Duroc breed was introduced to improve the growth characteristics of the Iberian pig, ⁎ Corresponding author. Tel.: +34 976 762738; fax: +34 976 761612. E-mail address: [email protected] (J.A. Beltrán).

http://dx.doi.org/10.1016/j.meatsci.2015.04.011 0309-1740/© 2015 Elsevier Ltd. All rights reserved.

which is recognized to produce high quality processed pork products in the national market (Oliver et al., 1994). Pig breeders and production systems have worked diligently towards higher production efficiency through genetic and feeding strategies and, as a result, carcass leanness has been increased, but some meat quality alterations (less intramuscular fat, lower water holding capacity of the muscle, lighter and tougher meat, etc.) have also occurred (Sosnicki, Pommier, Klont, Newman, & Plastow, 2003). Therefore, quantifying the effect that long-term intensive selection for increased carcass leanness has had on meat quality characteristics, some researchers (Schwab, Baas, Stalder, & Mabry, 2006) have recommended that selection practices should emphasise on pork quality (in addition to lean percentage) in commercial breeding programmes. For this reason, maintaining acceptable meat quality in the pork industry is becoming a relevant issue. Future success for the industry will require the production of consistent and predictable high product quality to ensure customer satisfaction. The target should be to combine efficient growth with the best possible meat quality or alternatively the aim can be described as optimizing meat quality with the lowest cost production (Plastow et al., 2005). Nowadays the pig carcass price is determined according to carcass classification methods or/and objective methods (for example: Fato-meater) whereby a good score is obtained when the backfat is reduced and a good conformation provides a high percentage of valuable cuts (Armero et al., 1999). For this reason, Pietrain pigs are used as terminal sires, but these animals can have a high susceptibility to stress, and decrease in technological and eating quality of pork. Many researchers have studied the effect of incorporating Duroc breed as sire

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line in crossbreeding on pig performance, meat quality and/or fatty acid composition (Alonso, Campo, Español, Roncalés, & Beltrán, 2009; Armero et al., 1999; Channon, Kerr, & Walker, 2004; Cilla et al., 2006; Latorre, Lázaro, Gracia, Nieto, & Mateos, 2003; Morcuende, Estévez, Ramírez, & Cava, 2007; Ramírez & Cava, 2007a). But only a few researchers (Blanchard, Warkup, Ellis, Willis, & Avery, 1999; Mörlein et al., 2007; Oliver et al., 1994) have focused on the effect of the inclusion of Duroc breed in maternal line in crossbreeding among white breeds to improve meat quality without decreasing lean growth. The objective of this study was to evaluate the effect of including different percentages of Duroc (D) breed in the maternal line (0%, 25% and 50%), as well as the effect of gender of animals, on meat quality, intramuscular and subcutaneous fatty acid composition and shear force in pork, as well as to examine the relationships among these traits.

2. Materials and methods The pigs used for this trial were cared in accordance with the guidelines from the Spanish Ministry of Agriculture (Boletín Oficial del Estado (BOE), 2007).

2.2. pH measurement Ultimate pH (pHu) of the LTL was measured using a portable pH meter equipped with a glass electrode Crison PH 25 (Crison instruments, Barcelona, Spain) at 48 h postmortem (p.m.). Each value was the mean of four measurements (in the middle of the muscle) that were carried out on Longissimus between the sixth and seventh thoracic (two measurements) and between the second and third lumbar (two measurements) vertebrae before slicing. 2.3. Instrumental measurement of colour A Minolta CM-2002 (Osaka, Japan) spectrophotometer was used to measure colour at the surface of a 2 cm-thick boneless loin chop at 48 h p.m. exposed to air for 2 h. The illuminant used was D65 and the standard observer position was 10°. The parameters registered were CIE L* (lightness), a* (redness), and b* (yellowness). Also, the hue angle (h°) and chroma (C*) indexes were calculated as: h° = tan − 1 (b* / a*), expressed in degrees, and C* = (a*2 + b*2)1/2. Each value was the mean of ten observations on the same chop, avoiding areas with excess fat. 2.4. Drip and cooking losses

2.1. Animals and sampling The experiment included a total of 59 pigs [29 entire males (EM) and 30 females] born from different dams inseminated with semen from the same Belgian Pietrain genetic line (n = 1). The maternal line changed depending on the inclusion of different percentages of the same Duroc pure line in the commercial crossbreeding (Landrace (LR) × Large White (LW)): a) 0% Duroc (LR × LW), b) 25% Duroc (LR × (LW × D)) and c) 50% Duroc (LR × D). During the growing-finishing period, all pigs were fed the same basal finisher diet (50% corn, 15.73% wheat, 8.01% soybean meal (47% CP), 7.72% sunflower meal (34% CP), 7.17% lupin, 3.89% rapeseed meal (34% CP), 2.12% palm kernel expeller, 2% animal fat (tallow–lard mix that had a 3/5 acidity grade) and a vitamin/ mineral source). The diet contained 16.6% crude protein, 5.33% crude fat, 0.95% lysine, and 14.37 MJ/kg digestible energy. Pigs had ad libitum access to feed and water. All groups of pigs were raised under similar conditions for 190 ± 5 days and transported to the farm to the slaughterhouse at approximately the same live weight, and at the same day. Animals were transported by truck (farms were located within 2 h of the slaughterhouse) in the evening and slaughtered the following morning after a resting period of 8 h and a total fasting period of 12 h. Twenty animals (n = 10 females; n = 10 entire males) from each one of the three maternal lines were randomly selected among 250 pigs (per crossbreeding) and slaughtered on the same day in a commercial facility. Pigs were stunned with CO2; following exsanguination, the carcasses were scalded, dehaired and eviscerated. The hot carcass weights had a mean value of 92.3 ± 3.9 kg [(a) LR × LW = 90.7 ± 4.5 kg; (b) LR × (LW × D) = 93.4 ± 2.5 kg; (c) LR × D = 92.3 ± 4.5 kg]. These carcasses included the head, skin, fore and hind trotters and did not include flare fats. No significant differences were found among crossbreeds in hot carcass weight values. The Longissimus thoracis et lumborum (LTL) was removed from each carcass immediately after quartering, 1–2 h after slaughter according to practise of the slaughterhouse. Also, a sample of subcutaneous fat (SCF) (outer and inner layers) was taken at the level of the thoracic ribs and frozen immediately. After 48 h at 4 ± 1 °C in a cooling chamber (airspeed: 1 m/s; 90% relative humidity), the LTL was sectioned into 2 cm-thick boneless pork chops from the caudal end for: potential of lipid oxidation, intramuscular fat (IMF) content, fatty acid composition, drip loss and muscle colour measurements. Also, a 6 cm-thick section was removed for Warner–Bratzler measurements. All samples (except those for colour and drip loss) were placed in vacuum bags and frozen at −20 °C until analysis.

A 2-cm-thick chop was weighed and placed on a supporting mesh in a sealed plastic container (with no contact between sample and container). After a storage period of 24 and 72 h at 4 ± 1 °C, the samples were taken out of the container, dabbed lightly on filter paper and weighed again. Drip loss was expressed as a percentage of the initial weight, based on Honikel (1998). Furthermore, cooking loss was determined in LTL chops that were weighed before and after grilling for Warner–Bratzler shear force determinations. 2.5. Potential of lipid oxidation Potential of lipid oxidation was measured by the 2-thiobarbituric acid (TBA) method of Pfalzgraf, Frigg, and Steinhart (1995). Meat samples of 10 g were taken and homogenized with 10% trichloroacetic acid using an Ultra-Turrax T25 (Janke & Kunkel, Staufen, Germany). Samples were centrifuged at 4000 rpm for 30 min at 10 °C and the supernatants filtered through quantitative paper. Two millilitres of the filtrates were taken and mixed with 2 ml of TBA (20 mM), homogenized and incubated for 20 min in boiling water. Absorbance was measured at 532 nm. The TBA-reactive substances (TBARS) values were calculated from a standard curve of malondialdehyde, and expressed as mg malondialdehyde/kg sample. 2.6. Intramuscular and subcutaneous fat and fatty acid analysis After LTL and SCF samples were fast-thawed in tap water (4 h, without losing vacuum), they were ground and 10 g of sample were weighted. The fat was extracted in chloroform-methanol (1:1 v/v), with 2,6-ditert-butyl-4-methylphenol (BHT) (1 g/10 ml methanol) as antioxidant (Bligh & Dyer, 1959). One millilitre of chloroform phase was used to assess the percentage of intramuscular fat (IMF) by drying at 100 °C for 20 min; the results were expressed as the weight percentage of wet muscle. The rest was evaporated in a sand bath under nitrogen gas at 50 °C. The methyl esters from fatty acids (FAMES) were formed using a KOH solution in methanol and collected in hexane for analysis by gas chromatography. The FAMES were analysed in a gas chromatograph HP-6890 II (Hewlett-Packard, Waldbronn, Germany) using a capillary column SP-2380 (100 m × 0.25 mm × 0.20 μm), and oven temperature programming as follows: column temperature was set at 140 °C, then raised at a rate of 3 °C/min from 130 to 158 °C, and 1 °C/min to 165 °C, kept for 10 min, raised at 165 to 220 °C and kept constant for 50 min. Nitrogen was used as a gas carrier at a constant flow rate

V. Alonso et al. / Meat Science 107 (2015) 49–56

of 0.8 ml/min with an injected volume of 1 μl. Fatty acid composition was quantified using nonadecanoic acid (C19:0) as the internal standard. 2.7. Warner–Bratzler shear force (WBSF) measurements Samples were fast-thawed in tap water for 4 h before the vacuum was broken, and the samples were wrapped in aluminium foil and cooked at 200 °C in a double-plate grill (Sammic GRS-5, Guipúzcoa, Spain) to an internal temperature of 72 °C. After cooking, boneless chops were placed in a vacuum bag and immediately immersed in an ice bath to stop further cooking until they reached room temperature (20 ± 2 °C). Twelve, 5-cm-long rectangles (1 cm2 cross section) were cut parallel to the direction of the muscle fibres, and subsequently sheared perpendicular to the muscle fibre direction with a 3 mm thick Warner–Bratzler shear blade attached to a TA-XT2 Texture Analyser (Stable Micro Systems, Godalming, UK) equipped with a 250-N load cell and a crosshead speed of 2 mm/s. The Texture Expert computer software (version 1.20; Stable Micro Systems) was used for data collection, and WBSF values were recorded as the maximum peak force of shearing (expressed in N). 2.8. Statistical analysis All data were statistically analysed by the General Linear Model (GLM) procedure of SPSS, version 19 (IBM SPSS, 2010). The model included maternal line and gender as main effects and their interaction. Duncan's post hoc test was used to assess differences between mean values when P ≤ 0.05. Mean values and standard errors of the means (SEM) are reported in all tables. Relationships among parameters of meat quality, intramuscular fatty acid composition and instrumental measurement of texture were performed by Principal Component Analysis (PCA) and were evaluated by calculating Pearson's correlation coefficients. PCA was applied using the statistical software XLSTAT, version Pro 7.5 (XLSTAT, 2004), and the Pearson's method using the statistical software SPSS. 3. Results and discussion 3.1. Meat quality 3.1.1. Effect of including Duroc breed in maternal line No significant interaction was observed between maternal line and gender for pH values, colour (L*, a*, b*, h° and C* values) and drip and cooking losses; therefore, only main effects are presented (Table 1). There was no effect (P N 0.05) of including Duroc in maternal line on pHu values, which agreed with Blanchard, Warkup, et al. (1999), Morcuende et al. (2007), Mörlein et al. (2007) and Oliver et al. (1994). However, some authors found that Duroc breed had higher pHu compared with white breeds when used as sire lines (Alonso et al., 2009;

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Latorre et al., 2003; Šimek et al., 2004) or pure lines (Oliver, Gispert, & Diestre, 1993). An increase in the percentage of Duroc genes did not affect L* values and hue angle (h°) in this study, which disagreed with Oliver et al. (1994), and Ramírez and Cava (2007a) who found that the inclusion of Duroc breed in dam line produced lower L* values. However, the majority of authors (Alonso et al., 2009; Channon et al., 2004; Latorre et al., 2003) had failed to detect differences in meat lightness when Duroc was used as sire line. On the contrary, LR × (LW × D) line had higher redness (a*) (P ≤ 0.05) than LR × D line and higher yellowness (b*) (P ≤ 0.01) and chroma (C*) values (P ≤ 0.05) than LR × D and LR × LW lines. No differences in b* values with the increase in the percentage of Duroc genes were reported by Alonso et al. (2009) and Oliver et al. (1994). Furthermore, Mörlein et al. (2007) did not find any difference in a* values between LW × LR and D × LR dam lines, which is in agreement with the current results. Some authors (Cameron, Warriss, Porter, & Enser, 1990; Gil et al., 2008; Newcom et al., 2004) found that Duroc and Large White breeds have higher a* values than Landrace. In fact, Duroc pure breed have higher myoglobin content than Landrace breed (Newcom et al., 2004), suggesting more red oxidative fibres in Duroc breed (Warris, Brown, Rolph, & Kestin, 1990). Furthermore, Large White breed have higher redness (Terlouw & Rybarczyk, 2008) and myoglobin content (Barton-Gade, 1987) than Duroc breed. In conclusion, the inclusion of Large White and Duroc breeds together in the same dam line could produce a more oxidative metabolism and explain the registered differences in colour characteristics of pork from this crossbreed. However, those differences in a* and b* values among the maternal lines would probably not be detectable by consumers; especially because meat red colour is more correlated to h° values than to a* or b* values (AMSA, 2012) and maternal line did not affect h° in the present study. Regarding water holding capacity (WHC), no significant differences (P N 0.05) were observed among maternal lines for 24- and 72-h drip loss. In agreement with our results, other authors did not obtain any difference in drip loss percentage when the content of Duroc genes was increased in dam line (Blanchard, Warkup, et al., 1999; Oliver et al., 1994) or in sire line (Armero et al., 1999; Channon et al., 2004). Other reports showed slightly better WHC for pigs containing some Duroc genes in dam line (Mörlein et al., 2007) or comparing Duroc and Large White pure breeds (Terlouw & Rybarczyk, 2008). The absence of differences in both colour and WHC are most probably related to the lack of effect of Duroc inclusion on pHu in our study. On the other hand, cooking loss percentage was not affected by increasing Duroc content in maternal line, which disagreed with Blanchard, Warkup, et al. (1999) and Mörlein et al. (2007). 3.1.2. Effect of gender There were no differences (P N 0.05) in pHu values and hue angle between genders (Table 1). The vast majority of previous research had

Table 1 Effect of maternal line and gender on pork quality parameters in Longissimus thoracis et lumborum: mean (x) and standard errors of the means (SEM). Maternal line

n pHu L* a* b* h° C* 24-h drip loss (%) 72-h drip loss (%) Cooking loss (%)

Sign.

LR × LW

LR × (LW × D)

LR × D

18 5.53 46.70 2.08ab 7.53a 75.56 7.88a 2.74 4.36 30.85

21 5.54 47.44 2.85b 8.65b 72.45 9.16b 2.94 4.05 28.79

20 5.53 47.10 1.94a 7.69a 76.67 8.02a 2.44 3.73 29.14

ns ns * ** ns * ns ns ns

Gender Entire males

Females

29 5.51 48.86b 2.62b 8.48b 73.84 8.95b 3.16b 4.62b 30.41

30 5.56 45.39a 2.01a 7.50a 75.84 7.84a 2.27a 3.47a 28.69

LW: Large White; LR: Landrace; D: Duroc; pHu: ultimate pH. Maternal line × Gender effects: no significant interaction. Different letters in the same row indicate significant differences among mean values; ns = P N 0.1; * = P ≤ 0.05; ** = P ≤ 0.01; *** = P ≤ 0.001.

Sign.

SEM

ns *** * ** ns ** ** ** ns

0.02 0.47 0.18 0.18 0.90 0.21 0.16 0.22 0.55

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failed to detect pH differences between entire male (EM) and female pigs (Armero et al., 1999; Barton-Gade, 1987; Blanchard, Ellis, Warkup, Chadwick, & Willis, 1999; Gispert et al., 2010; Ramírez & Cava, 2007a). Meanwhile, meat from EM had higher L* (P ≤ 0.001), a* (P ≤ 0.05), b* (P ≤ 0.01) and h° (P ≤ 0.01) values than female pigs, which is in agreement with Gispert et al. (2010) who found that EM had greater a* values than female pigs. This is in contrast with Armero et al. (1999) and Ramírez and Cava (2007a) who observed no differences between EM and female pigs in terms of colour measurement. On the other hand, both 24- and 72-h drip loss percentages were lower (P ≤ 0.01) in female than EM pigs. No significant differences (P N 0.05) were observed between genders for cooking loss percentage. Previous research (Blanchard, Ellis, et al., 1999; Ramírez & Cava, 2007a) had failed to detect differences between EM and female pigs in drip and cooking losses. However, Channon et al. (2004) did not find any difference in drip loss, while cooking loss was higher in EM than in female pigs.

3.1.3. Maternal line-gender interaction for TBARS and WBSF values A significant interaction, maternal line × gender, was observed in TBARS values (P ≤ 0.05) and WBSF (P ≤ 0.001) (Table 2). There is not much literature published concerning the effect of crossbreeding and gender on lipid oxidation values. There were no significant differences among entire males from three crosses for TBARS values. However, female pigs from LR × LW and LR × D lines had higher (P ≤ 0.01) potential of lipid oxidation than LR × (LW × D) line. Ramírez and Cava (2007b) reported that the potential of lipid oxidation values did not show any difference between entire male and female pigs; meanwhile, chops from Duroc sire line (meat production) × Iberian dam line had higher potential of lipid oxidation than Iberian sire line × Duroc dam line (drycured-meat products). In this study, EM pigs from 50% Duroc dams had lower (P ≤ 0.001) WBSF values than EM from 0% and 25% Duroc dams. Meanwhile, female pigs from 25% and 50% Duroc dams had lower (P ≤ 0.001) WBSF values than females from 0% Duroc dams. The majority of available research (Barton-Gade, 1987; Blanchard, Warkup, et al., 1999; Latorre et al., 2003; Mörlein et al., 2007) found that an increase of Duroc breed genes in crossbreeding reduced the resistance to cutting of pork, which was in agreement with the current results. This was probably related to the greatest IMF content found in the crossbreeding with Duroc genes. Regarding WBSF results, the highest values found in our study could be explained by the type of quartering. The M. LTL was removed from each carcass immediately after quartering (1–2 h after slaughter). This type of ‘hot’ quartering produces higher drip losses than ‘cold’ quartering and higher contraction of muscle fibers; therefore, a higher resistance to cutting would be expected. Table 2 Maternal line–gender interaction for the content of mg of malondialdehyde/kg (TBARS values) and Warner–Bratzler shear force (WBSF) determinations of pork in M. Longissimus thoracis et lumborum. Maternal line effect

Sign.

LR × LW

LR × (LW × D)

LR × D

TBARS values Entire males Females Sign.

0.067a 0.077bz *

0.073 0.063y t

0.079 0.086z ns

ns **

WBSF (N) Entire males Females Sign.

76.4z 75.2z ns

77.0bz 61.0ay ***

60.8y 66.0y t

*** ***

SEM

0.013 0.017

10.36 8.35

x: Means; SEM: standard errors of the means; LW: Large White; LR: Landrace; D: Duroc; TBARS: TBA-reactive substances. Different letters in the same column indicate significant differences between mean values of gender: a, b; different letters in the same row indicate significant differences among mean values of maternal line: y, z; ns = P N 0.1; t = P ≤ 0.1; * = P ≤ 0.05; ** = P ≤ 0.01; *** = P ≤ 0.001.

3.2. Intramuscular fat content and fatty acid composition 3.2.1. Effect of including Duroc breed in maternal line IMF content was higher (P ≤ 0.001) in pork from LR × D line than in pork from LR × LW and LR × (LW × D) maternal lines (Table 3). This suggests that increasing Duroc genes in maternal line results in increasing IMF. In fact, numerous authors have found that the inclusion of the Duroc breed resulted in increased IMF levels compared with white breeds when used as dam line (Blanchard, Warkup, et al., 1999; Mörlein et al., 2007; Oliver et al., 1994), as sire line (Alonso et al., 2009; Armero et al., 1999; Barton-Gade, 1987; Latorre et al., 2003; Šimek et al., 2004) or pure line (Cameron et al., 1990; Channon et al., 2004; Gil et al., 2008; Oliver et al., 1993). Differences among maternal lines were significant (Table 3) when comparing concentrations (expressed as a percentage) of most individual fatty acids in the IMF. The stearic (C18:0; P ≤ 0.01) and palmitic (C16:0; P ≤ 0.05) acids, and the sum of total saturated fatty acids (SFA; P ≤ 0.01) were significantly higher when Duroc was included in dam line. In agreement with the present results, many authors found that Duroc breed had higher C16:0, C18:0 and/or SFA percentages compared with other white breeds (Landrace, Large White and Pietrain (P)) when it was used as sire line (Alonso et al., 2009) or pure line (Cameron & Enser, 1991; Plastow et al., 2005; Zhang et al., 2007). The proportion of oleic acid (C18:1n − 9; P ≤ 0.01) and monounsaturated fatty acids (MUFA; P ≤ 0.05) was also higher when increasing Duroc genes. Several authors (Cameron & Enser, 1991; Pascual et al., 2007; Zhang et al., 2007) found that Duroc pure breed had greater C16:1n − 9, C18:1n − 9 and/or MUFA percentages than LW, LR or P. In contrast, the sum of total n − 6 polyunsaturated fatty acid (PUFA; P ≤ 0.01), such as linoleic (C18:2; P ≤ 0.05) and arachidonic (C20:4; P ≤ 0.001) acids, and the sum of total n − 3 PUFA (P ≤ 0.001), such as eicosapentaenoic acid, EPA (C20:5; P ≤ 0.001) and docosapentaenoic acid, DPA (C22:5; P ≤ 0.001), were significantly lower when Duroc was included in dam line. Previous research (Alonso et al., 2009; Cameron & Enser, 1991; Pascual et al., 2007; Plastow et al., 2005; Zhang et al., 2007) had found that Duroc breed produced pork with the lowest percentage of C18:2n − 6 and C20:4n − 6 compared to LR or LW pure breeds or other white breed crosses. More specifically, there was only a slight tendency for α-linolenic acid (C18:3n − 3) to be higher in LR × D line than in LR × (LW × D) line, while LR × LW line had an intermediate value. Some authors (Alonso et al., 2009; Cameron & Enser, 1991) had failed to detect differences in α-linolenic acid percentage among Landrace, Large White, Duroc, Pietrain and their crossbreeding. The amounts of most individual fatty acids (mg of fatty acids per 100 g of muscle) are showed in Table 4. The pigs from LR × D dam line produced lipids with higher (P ≤ 0.001) content of C16:0, C18:0, C16:1, C18:1n − 9, C18:2n − 6, C18:3n − 3 and the majority of long chain fatty acids and showed, consequently, higher level of total SFA, MUFA and PUFA. Those results were due to the highest IMF percentage found in that dam line. Fatty acid ratios relevant to human health are also shown in Table 3. Nutritional recommendations for a healthy diet suggest that the ratio of P/S (PUFA/SFA) should be N 0.4 and intakes of n − 3 PUFA should be increased relative to n − 6 PUFA (maximum n − 6/n − 3 ratio = 4) (Department of Health, 1994). Pork is characterised by a high content of C18:2n − 6 in a cereal-based diet, which leads to acceptable P/S ratio, but the high content in n − 6 PUFA as found in the present study, usually results in undesirably high n − 6/n − 3 ratio from a human health perspective (Wood et al., 2003). These statements agreed with our results, where pork from three dam lines had a favourable P/S ratio from a nutritional point of view, but high n − 6/n − 3 ratio. 3.2.2. Effect of gender There were no differences (P N 0.05) in IMF content between EM and female pigs, which agreed with Armero et al. (1999), Barton-Gade

V. Alonso et al. / Meat Science 107 (2015) 49–56

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Table 3 Effect of maternal line and gender on intramuscular fat content and fatty acid composition (% of total fatty acids) in Longissimus thoracis et lumborum: mean and standard errors of the means (SEM). Maternal line

n IMF C12:0 C14:0 C16:0 C16:1 C18:0 C18:1 n − 9 C18:1 n − 7 C18:2 n − 6 C18:3 n − 6 C18:3 n − 3 C20:1 n − 9 C20:2 n − 6 C20:2 n − 3 C20:3 n − 6 C20:3 n − 3 C20:4 n − 6 C20:5 n − 3 C22:5 n − 3 C22:6 n − 3 ∑SFA ∑MUFA ∑PUFA ∑n − 6 ∑n − 3 P/S ratio n − 6/n − 3 ratio

Sign.

LR × LW

LR × (LW × D)

LR × D

18 1.54a 0.08a 1.07a 22.27a 2.43 10.03a 34.36a 3.63 16.94b 0.11b 0.37 0.71 0.52c 0.15b 0.39b 0.10b 3.38b 0.09b 0.42b 0.08b 34.20a 41.66a 23.20b 21.37b 1.20b 0.68b 17.83a

21 1.79a 0.08a 1.15a 22.87b 2.50 10.98b 36.78b 3.51 14.64a 0.12b 0.34 0.68 0.42a 0.12a 0.33a 0.07a 2.53a 0.07a 0.28a 0.07ab 35.80b 43.96b 19.50a 18.05a 0.94a 0.55a 19.15b

20 2.39b 0.09b 1.29b 22.91b 2.48 11.24b 37.15b 3.53 14.44a 0.08a 0.39 0.71 0.48b 0.10a 0.28a 0.08ab 2.06a 0.05a 0.28a 0.06a 36.24b 44.37b 18.73a 17.36a 0.96a 0.52a 18.10a

*** *** *** * ns ** ** ns * *** t ns *** *** *** * *** *** *** * ** * ** ** *** *** ***

Gender Entire males

Females

29 1.82 0.09 1.17 22.52 2.41 10.88 35.06a 3.49 16.16b 0.10 0.39b 0.70 0.51b 0.13 0.35 0.08 2.79 0.07 0.34 0.07 35.40 42.19a 21.57b 19.93b 1.08 0.62b 18.50

30 2.02 0.08 1.18 22.88 2.54 10.69 37.23b 3.62 14.42a 0.10 0.35a 0.69 0.43a 0.11 0.32 0.08 2.47 0.07 0.30 0.07 35.52 44.56b 19.21a 17.76a 0.97 0.55a 18.29

Sign.

SEM

ns t ns ns ns ns ** ns * ns * ns *** t ns ns ns ns ns ns ns ** * * t * ns

0.078 0.002 0.023 0.112 0.053 0.151 0.412 0.046 0.405 0.004 0.009 0.010 0.011 0.005 0.012 0.004 0.131 0.003 0.015 0.003 0.248 0.474 0.592 0.541 0.031 0.020 0.129

SEM: standard errors of the means; IMF: percentage of intramuscular fat extracted by Bligh and Dyer method; LW: Large White; LR: Landrace; D: Duroc; SFA: Saturated fatty acids; MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids; P/S: PUFA/SFA ratio. Maternal line × Gender effects: no significant interaction. Different letters in the same row indicate significant differences among mean values; ns = P N 0.1; t = P ≤ 0.1; * = P ≤ 0.05; ** = P ≤ 0.01; *** = P ≤ 0.001.

Table 4 Effect of maternal line and gender on fatty acid composition of intramuscular fat (mg/100 g muscle) in Longissimus thoracis et lumborum: mean and standard errors of the means (SEM). Maternal line

n C12:0 C14:0 C16:0 C16:1 C18:0 C18:1 n − 9 C18:1 n − 7 C18:2 n − 6 C18:3 n − 6 C18:3 n − 3 C20:1 n − 9 C20:2 n − 6 C20:2 n − 3 C20:3 n − 6 C20:3 n − 3 C20:4 n − 6 C20:5 n − 3 C22:5 n − 3 C22:6 n − 3 ∑SFA ∑MUFA ∑PUFA ∑n − 6 ∑n − 3

Sign.

LR × LW

LR × (LW × D)

LR × D

18 0.79a 11.30a 227.17a 25.39a 102.63a 356.97a 37.16a 165.33a 1.043a 3.77a 7.32a 5.19a 1.41ab 3.76a 0.89a 31.75 0.83 3.93b 0.79 349.58a 432.78a 224.87a 207.29a 11.63a

21 0.99a 14.44a 281.33a 30.96a 135.46a 456.37a 43.10a 174.33a 1.36b 4.22a 8.42a 5.19a 1.32a 3.87a 0.80a 29.2 0.77 3.29a 0.79 440.95a 545.28a 231.20a 214.16a 11.19a

20 1.64b 22.85b 398.70b 43.62b 198.13b 656.22b 61.17b 238.71b 1.29b 6.72b 12.44b 8.04b 1.58b 4.54b 1.34b 32.3 0.86 4.35c 0.93 633.51b 782.61b 307.59b 285.18b 15.88b

*** *** *** *** *** *** *** *** ** *** *** *** * *** *** ns ns *** ns *** *** *** *** ***

Gender Entire males

Females

29 1.12 15.23 281.51 30.31a 138.49 445.36a 42.98a 192.35 1.13a 4.95 8.82 6.29 1.43 3.98 0.98 30.61 0.77a 3.8 0.76a 445.72 534.39a 253.53 234.61 12.70

30 1.18 17.4 326.91 36.67b 154.48 540.60b 51.70b 194.43 1.34b 4.91 10.05 6.02 1.44 4.14 1.03 31.44 0.86b 3.89 0.92b 509.89 646.53b 256.75 237.62 13.05

Sign.

SEM

ns ns t * ns * * ns ** ns ns ns ns ns ns ns ** ns * ns * ns ns ns

0.075 1.064 15.988 1.939 8.886 29.017 2.438 7.053 0.043 0.284 0.533 0.298 0.039 0.095 0.049 0.632 0.019 0.098 0.036 26.325 34.114 8.296 7.767 0.440

SEM: standard errors of the means; LW: Large White; LR: Landrace; D: Duroc; SFA: Saturated fatty acids; MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids. Maternal line × Gender effects: no significant interaction. Different letters in the same row indicate significant differences among mean values; ns = P N 0.1; t = P ≤ 0.1; * = P ≤ 0.05; ** = P ≤ 0.01; *** = P ≤ 0.001.

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V. Alonso et al. / Meat Science 107 (2015) 49–56

(1987), Blanchard, Ellis, et al. (1999), Gispert et al. (2010) and Ramírez and Cava (2007a). The fatty acid composition of the IMF for EM and females is shown in Table 3. No differences due to gender were detected for C16:0, C18:0, C16:1n − 9 and total SFA. The proportion of C18:1n − 9 and total MUFA was higher (P ≤ 0.01) in females than in EM pigs. However, the concentrations of linoleic and α-linolenic acids were higher (P ≤ 0.05) in EM than in female pigs, which caused an increase in the proportions of both n − 6 and n − 3 PUFA. No significant differences were found between genders for the majority of long chain fatty acid proportions (C20–C22). However, the total sum of PUFA was higher (P ≤ 0.05) in EM pigs. Cameron and Enser (1991) found that female had higher C16:0, C18:0, C16:1, C18:1n − 9, SFA and MUFA than EM pigs; meanwhile, the C18:2n − 6, C18:3n − 3, C20:4n − 6, C22:5n − 3, C22:6n − 3 and PUFA proportions were higher in EM than in female pigs. This is in contrast with Ramírez and Cava (2007a) who did not report any differences between EM and female Iberian crossbreeding pigs in the IMF fatty acid profile. Furthermore, females had only higher (P ≤ 0.05) amount of MUFA than EM when results were expressed as mg/100 g muscle (Table 4). In relation to human healthy indexes, there were differences in the PUFA/SFA ratio, with the highest ratio in entire males, but no significant differences were observed for the n − 6/n − 3 ratio. 3.3. Subcutaneous fatty acid composition 3.3.1. Effect of including Duroc breed in maternal line The fatty acid composition of the subcutaneous fat (SCF) is shown for the three maternal lines in Table 5. The concentrations of C18:0 (P ≤ 0.01) and SFA (P ≤ 0.001) were higher when Duroc was included in dam line; meanwhile, no significant differences were observed among crossbreeds in the C16:1, C18:1n − 9 and total sum of MUFA percentages. Several authors (Cameron & Enser, 1991; Pascual et al., 2007) found that Landrace pure breed had greater C16:0, C18:0 and

C18:1n − 9 percentages than LW or D; meanwhile, Duroc breed had the greatest C16:1 percentage. Alonso et al. (2009) and Barton-Gade (1987) reported that Duroc sire line produced the lowest C16:0, C18:0 and SFA percentages compared to LW sire line. However, Barton-Gade (1987) found the LW sire line had higher oleic acid and MUFA than Duroc sire line; whereas, Alonso et al. (2009) did not found any difference. Furthermore, proportions of C18:2n − 6 and sum of total n − 6 and PUFA were lower (P ≤ 0.01) when Duroc breed was included in dam line. In contrast, Alonso et al. (2009), Barton-Gade (1987) and Cameron et al. (1990) reported that Duroc pure breed or sire line had greater percentages of linoleic acid than LR and LW pure breed or LW sire line. However, Pascual et al. (2007) did not find any difference in this fatty acid among LR, D and LW pure breed. The percentages of C18:3n − 3, EPA and the sum of n − 3 were higher (P ≤ 0.001) in LR × D and LR × LW lines than in LR × (LW × D) line. The Duroc pure breed has been reported to have a greater α-linolenic acid percentage compared to LW (Barton-Gade, 1987) or LR (Cameron et al., 1990) breeds. In contrast, Alonso et al. (2009) did not find any difference among Duroc and Large White sire lines mated with the same maternal line (LR × LW) in C18:3n − 3, EPA and the sum of n − 3 proportions. 3.3.2. Effect of gender The results for backfat fatty acid composition according to gender are shown in Table 5. The concentration of C16:0 were higher (P ≤ 0.05) in entire males than in female pigs, but no differences were found in C18:0 and SFA percentages. The proportion of oleic acid and MUFA was higher (P ≤ 0.001) in female than in EM pigs. In contrast, EM had the greatest percentages of C18:2n − 6, the total sum of n −6 and PUFA (P ≤ 0.01) and C18:3n − 3 and the sum of n − 3 (P ≤ 0.05). Those results agreed with previous reports that found that the SFA and MUFA contents were higher, whereas the PUFA content was lower, in females compared to EM (Barton-Gade, 1987; Cameron & Enser, 1991; Hallenstvedt, Kjos, Øverland, & Thomassen, 2012).

Table 5 Effect of maternal line and gender on fatty acid composition of subcutaneous fat (% of total fatty acids): mean and standard errors of the means (SEM). Maternal line

n C12:0 C14:0 C16:0 C16:1 C18:0 C18:1 n − 9 C18:1 n − 7 C18:2 n − 6 C18:3 n − 6 C18:3 n − 3 C20:1 n − 9 C20:2 n − 6 C20:2 n − 3 C20:3 n − 6 C20:3 n − 3 C20:4 n − 6 C20:5 n − 3 C22:5 n − 3 C22:6 n − 3 ∑SFA ∑MUFA ∑PUFA ∑n − 6 ∑n − 3 P/S ratio n − 6/n − 3 ratio

Sign.

LR × LW

LR × (LW × D)

LR × D

18 0.12a 1.22a 19.96a 1.60 9.42a 37.78 2.26b 21.53b 0.06b 0.92b 0.77b 0.81b 0.031b 0.14b 0.14b 0.33 0.01 0.09b 0.02 31.77a 43.17 24.24b 22.89b 1.21b 0.76b 18.92b

21 0.13b 1.29b 20.65b 1.50 10.50b 38.05 2.13a 20.24a 0.06ab 0.84a 0.72a 0.75a 0.027a 0.13a 0.11a 0.31 0.01 0.07a 0.02 33.49b 43.07 22.69a 21.49a 1.08a 0.68a 19.89c

20 0.13b 1.32b 20.35ab 1.59 10.20b 38.27 2.32b 20.31a 0.05a 0.90b 0.75ab 0.79ab 0.028ab 0.13a 0.13b 0.31 0.01 0.08b 0.02 32.90b 43.60 22.92a 21.61a 1.18b 0.70a 18.31a

* ** * ns ** ns ** ** * *** * * * *** *** ns ns *** ns *** ns ** ** *** *** ***

Gender Entire males

Females

29 0.14a 1.31b 20.56b 1.55 10.02 37.20a 2.21 21.30b 0.05 0.90b 0.76 0.8 0.030b 0.13 0.13 0.32 0.01 0.08 0.02 33.02 42.42a 23.94b 22.63b 1.18b 0.73 19.25

30 0.12b 1.25a 20.12a 1.57 10.11 38.86b 2.26 20.03a 0.06 0.86a 0.73 0.77 0.027a 0.13 0.12 0.32 0.01 0.08 0.02 32.52 44.11b 22.57a 21.32a 1.13a 0.70 18.87

Sign.

SEM

*** * * ns ns *** ns ** ns * ns ns * ns ns ns ns ns ns ns *** ** ** * t t

0.002 0.013 0.110 0.028 0.131 0.202 0.024 0.200 0.002 0.010 0.009 0.001 0.002 0.003 0.005 0.005 0.001 0.001 0.001 0.204 0.237 0.219 0.208 0.012 0.009 0.135

SEM: standard errors of the means; LW: Large White; LR: Landrace; D: Duroc; SFA: Saturated fatty acids; MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids; P/S: PUFA/SFA ratio. Maternal line × Gender effects: no significant interaction. Different letters in the same row indicate significant differences among mean values; ns = P N 0.1; t = P ≤ 0.1; * = P ≤ 0.05; ** = P ≤ 0.01; *** = P ≤ 0.001.

V. Alonso et al. / Meat Science 107 (2015) 49–56

In conclusion, an increase in the percentage of Duroc genes in maternal line produced a similar effect in both IMF and SCF, with increased SFA and decreased PUFA percentages; whereas, the maternal line effect did not reach significance on MUFA percentage in SCF. Furthermore, the effect of gender was similar in both IMF and SCF, with female pigs having the highest MUFA and the lowest PUFA percentages. However, gender did not affect the percentage of SFA in both fat deposits. 3.4. Descriptive principal component analysis (PCA) for pork quality, IMF fatty acid composition and texture The principal component analysis (PCA) explained 72.6% of the variability of the results within the first two axes. The projection of the observations of maternal lines and gender, together with parameters of meat quality, intramuscular fatty acid composition (% of total fatty acids) and WBSF studied in the plane defined by the first two principal components are shown in Fig. 1. Also, the projection of additional illustrative variables as chroma, hue and sum of total SFA, MUFA and n − 6 and n − 3 PUFA are depicted in Fig. 1. The first PC (PC1) was able to explain 50.7% of the variation of the whole study. This component is mainly characterised by C16:0 and C18:1n − 9 fatty acids and IMF percentage on the negative side, and C18:2n − 6, the majority of long chain fatty acids studied in this trial, P/S ratio and WBSF on the positive side. The maternal lines with Duroc breed inclusion were nearly located on the left quadrants of the figure; meanwhile, the maternal line without Duroc breed was clearly differentiated from the rest of the lines and was positively placed in the right quadrants of the figure. IMF was correlated (P ≤ 0.001) positively with C16:0 (0.35), C18:0 (0.47), C18:1n − 9 (0.67), SFA (0.51) and MUFA (0.61) and negatively with C18:2n − 6 (− 0.52), C20:4n − 6 (− 0.77), C20:5n − 3 (− 0.73), C22:6n − 3 (−0.57), PUFA (−0.69), and P/S ratio (−0.68).

1 0,9

L* C18:3n-3

0,8

C12:0

0,7

24-h Drip loss

0,6 0,5 0,4

PC 2 (21.9 %)

0,3 0,2

b*

C18:0

C*

C14:0 SFA

-0,3 -0,4 -0,5

n-6/n-3

C20:3n-3

C18:2 n-6

n-3

WBSF

C20:2n-3 C22:5n-3 C20:3n-6

h° C16:0 C18:1n-9 MUFA

n-6 PUFA P/S

C20:4n-6 C20:5n-3 C16:1

C22:6n-3 C18:3n-6

-0,6 -0,7

Cooking loss

a*

0

-0,2

C20:1n-9

TBARS

IMF

0,1

-0,1

C20:2n-6 72-h Drip loss

pHu

C18:1n-7

-0,8 -0,9 -1

-1 -0,9-0,8-0,7-0,6-0,5-0,4-0,3-0,2-0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

PC 1 (50.7 %)

Fig. 1. (●) Projection of active variables: parameters of meat quality, intramuscular fat content, IMF fatty acid composition (% of total fatty acids) and Warner–Bratzler shear force; ( ) projection of additional illustrative variables: Chroma, hue and sum of total saturated, monounsaturated and n − 6 and n − 3 polyunsaturated fatty acids; and projection of the observations of the three maternal lines studied (values divided by 7) in the plane defined by two principal components: a) LR × LW (♦: females; : entire males); b) LR × (LW × D) (■: females; : entire males) and c) LR × D (▲: females; : entire males). LR: Landrace; LW: Large White; D: Duroc. pHu: ultimate pH; TBARS: TBA-reactive substances; IMF: percentage of intramuscular fat extracted by Bligh & Dyer method; WBSF: Warner–Bratzler shear force; SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; P/S ratio: PUFA/SFA ratio.

55

Those results agreed with previous reports that found that the contents of SFA and MUFA increased faster with increasing fatness (compared with PUFA content), resulting in a decrease in the relative proportion of PUFA. PUFA are a main phospholipid component, which are strictly controlled in order to preserve membrane properties and thus maintained relatively constant. However, the PUFA content of TG is diluted by de novo fatty acid synthesis consisting of SFA and MUFA, thus causing a decline in the P/S ratio with increasing fat deposition (De Smet, Raes, & Demeyer, 2004). In this regard, pigs from maternal lines with Duroc genes were located on the left quadrants of the figure, close to IMF, SFA and MUFA. Conversely, females and EM from LR × LW maternal line were clearly differentiated from the rest of groups and were positively placed in the right-lower quadrant of the figure, together with PUFA, C18:2n − 6, n − 6, n − 3 and P/S ratio and close to WBSF. Essén-Gustavsson, Karlsson, Lundström, and Enfält (1994) suggested that the infiltration of IMF within the perimysium connective tissue weakened the crosslinkage between collagen fibres, reducing the force required to break down the connective tissue. Thus, the location of marbling fat in the perimysial connective tissue between muscle fibre bundles may be decisive to ‘open up’ the muscle structure, making it easier to break in the mouth (Wood, 1990). This fact is supported by the negative correlation (− 0.28; P = 0.033) between WBSF and IMF content. Furthermore, WBSF was negatively correlated with the amount of SFA (−0.28; P = 0.033) and MUFA (−0.27; P = 0.042) expressed as mg/100 g muscle. A high amount of oleic acid and MUFA were produced as IMF increased, as was previously reported. MUFA have a lower melting point than SFA and, therefore, fat firmness would be lower as the amount of MUFA increased; subsequently, resistance to cutting was lower. Also, cooking loss was positively correlated with WBSF (0.36; P = 0.005), which is likely the result of denaturation of muscle proteins that bind water and the shrinkage of collagen and stromal proteins in the extracellular matrix; therefore, the resistance to shearing of pork was higher as cooking loss increased. Alonso, Campo, Provincial, Roncalés, and Beltrán (2010) confirmed that WBSF was a good index of the tenderness for grillcooked pork. In fact, they obtained a greater correlation between WBSF and tenderness (−0.81), juiciness (−0.56) and overall acceptance (−0.50). Therefore, animals with lower WBSF values, as were EM and females from LR × D line and females from LR × (LW × D) line, could have a higher sensory tenderness and juiciness. In contrast, EM from LR × LW line had a higher cooking loss and WBSF values and would be expected to have tougher meat than females. Regarding lipid oxidation, there were positive correlations of TBARS values with IMF (0.34; P = 0.009) and the amount of MUFA (0.32; P = 0.014), PUFA (0.34; P = 0.008), n − 6 (0.34; P = 0.008) and n − 3 (0.36; P = 0.005) expressed as mg/100 g muscle. It is well-known that lipid oxidation in pork depends on the fatty acid composition of lipids and is initiated in phospholipids in cellular membranes. Lipid oxidation is a complex process in which molecular oxygen reacts with unsaturated fatty acids, particularly with PUFA. In our study, females and entire males from LR × D line had the greatest values of IMF and also potential of lipid oxidation. It could be due to the fact that the amount of MUFA and PUFA were higher as IMF content increased; therefore, there was a higher amount of PUFA to begin lipid oxidation. The second PC explained 21.9% of the variability and was characterised by the fact that pH values were negatively correlated (P ≤ 0.001) with percentage of 24-h and 72-h drip loss (− 0.60; − 0.68) and L* and b* values (− 0.61; − 0.59). It is generally accepted that water holding capacity decreases as muscle pHu decreases, resulting in increased muscle surface exudate or drip loss (Lawrie, 1998). Furthermore, a high ultimate pH alters the absorption properties of meat, the meat surface becoming darker red (Lawrie, 2006). Consequently, lightness and drip loss were higher as pH values decreased which could reduce the quality of pork from EM, which were nearly placed on the right-upper quadrant and related to drip loss and L*, b* and C* values.

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V. Alonso et al. / Meat Science 107 (2015) 49–56

4. Conclusions An increase in the percentage of Duroc genes in maternal line did not affect pH values, lightness and drip and cooking losses; meanwhile, it resulted in finishing pigs that had meat with a higher intramuscular fat content, a lower resistance to cutting, and a slightly higher potential of lipid oxidation. Moreover, the presence of Duroc breed in maternal line provided significant changes in intramuscular and subcutaneous fatty acid profile, producing a higher saturated and monounsaturated and a lower polyunsaturated fat. Regarding the effect of gender, entire males had the greatest L*,a* and b* values and the lowest water holding capacity; whereas, females had a higher potential of lipid oxidation. However, the effect of gender on fatty acid profile had a lesser significance, being fat from females more monounsaturated and lower polyunsaturated than entire males. Based on the results from this study, the inclusion of Duroc breed in maternal lines could provide an improvement in fresh pork or dry meat products quality, by increasing the intramuscular fat content and potentially sensory tenderness, while maintaining a nutritionally favourable PUFA/SFA relation. Acknowledgements The authors thank Cincaporc S.A. company for financial support. We also thank the Meat and Fish Technology Laboratory (especially P. Marquina) at the Faculty of Veterinary for their scientific and technical assistance. References Alonso, V., Campo, M.M., Español, S., Roncalés, P., & Beltrán, J.A. (2009). Effect of crossbreeding and gender on meat quality and fatty acid composition in pork. Meat Science, 81, 209–217. Alonso, V., Campo, M.M., Provincial, L., Roncalés, P., & Beltrán, J.B. (2010). Effect of protein level in commercial diets on pork meat quality. Meat Science, 85, 7–14. AMSA (2012, December). In M. Hunt, & D. King (Eds.), Meat color measurement guidelines (pp. 136). Champaign, Illinois USA: American Meat Science Association. Armero, E., Flores, M., Toldrá, F., Barbosa, J.A., Olivet, J., Pla, M., & Baselga, M. (1999). Effects of pig sire type and sex on carcass traits, meat quality and sensory quality of dry-cured ham. Journal of the Science of Food and Agriculture, 79, 1147–1154. Barton-Gade, P.A. (1987). Meat and fat quality in boars, castrates and gilts. Livestock Production Science, 16, 187–196. Blanchard, P.J., Ellis, M., Warkup, C.C., Chadwick, J.P., & Willis, M.B. (1999a). The influence of sex (boars and gilts) on growth, carcass and pork eating quality characteristics. Animal Science, 68, 487–493. Blanchard, P.J., Warkup, C.C., Ellis, M., Willis, M.B., & Avery, P. (1999b). The influence of the proportions of Duroc genes on growth, carcass and pork eating quality characteristics. Animal Science, 68, 495–501. Bligh, E.G., & Dyer, W.J. (1959). A rapid method of total lipid extraction and purification. Canadian Journal of Biochemistry and Physiology, 37, 911–914. Boletín Oficial del Estado (BOE) (2007). Ley Española 32/2007 sobre el cuidado de los animales, en su explotación, transporte, experimentación y sacrificio. Boletin Oficial del Estado, 268, 45914–45920. Cameron, N.D., & Enser, M.B. (1991). Fatty acid composition of lipid in Longissimus dorsi muscle of Duroc and British Landrace pigs and its relationship with eating quality. Meat Science, 29, 295–307. Cameron, N.D., Warriss, P.D., Porter, S.J., & Enser, M.B. (1990). Comparison of Duroc and British Landrace pigs for meat and eating quality. Meat Science, 27, 227–247. Channon, H.A., Kerr, M.G., & Walker, P.J. (2004). Effect of Duroc content, sex and ageing period on meat and eating quality attributes of pork loin. Meat Science, 66, 881–888. Cilla, I., Altarriba, J., Guerrero, L., Gispert, M., Martínez, L., Moreno, C., Beltrán, J.A., Guàrdia, M.D., Diestre, A., Arnau, J., & Roncalés, P. (2006). Effect of different Duroc line sires on carcass composition, meat quality and dry-cured ham acceptability. Meat Science, 72, 252–260. De Smet, S., Raes, K., & Demeyer, D. (2004). Meat fatty acid composition as affected by fatness and genetic factors: A review. Animal Research, 53, 81–98. Department of Health (1994). Nutritional aspects of the cardiovascular disease. Report of health and social subjects No. 46. London: Her Majesty's Stationery Office. Edwards, S.A., Wood, J.D., Moncrieff, C.B., & Porter, S.J. (1992). Comparison of the Duroc and Large White as terminal sire breeds and their effect on pig meat quality. Animal Production, 52, 289–297. Essén-Gustavsson, B., Karlsson, A., Lundström, K., & Enfält, A.C. (1994). Intramuscular fat and muscle fibre lipid contents of halothane gene free pigs fed high or low protein diets and its relation to meat quality. Meat Science, 38, 269–277. Gil, M., Delday, M.I., Gispert, M., Font i Furnols, M., Maltin, C.M., Plastow, G.S., Klont, R., Sosnicki, A.A., & Carrión, D. (2008). Relationships between biochemical

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